JPH0563535A - Semiconductor relay - Google Patents

Abstract

PURPOSE:To realize the semiconductor relay for both AC and DC use by supplying a base current of Darlington connection transistors(TRs) when two photodiodes connected in opposite polarity coupled optically with a light emitting means connected between relay input terminals are conductive. CONSTITUTION:When an input signal is applied between relay input terminals 1, 2, photodiodes 6-9 are conductive through exposure of light from a light emitting diode 5. As a result, any of two TRs 10, 11 in Darlington connection is biased depending on the polarity of the voltage between relay output terminals 3, 4 and conductive and a current flows between the output terminals 3, 4. When the input signal is interrupted, both two TRs 10, 11 are nonconductive, the current flowing between the relay output terminals 3, 4 is interrupted. Thus, even when a DC power supply or an AC power supply is employed for a load to be controlled, the power supply is self-extincted and the semiconductor relay is formed by PN junction only and the semiconductor relay of a large capacity is easily formed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor relay in which input and output are insulated by light.

[0002]

2. Description of the Related Art Conventionally, a thyristor Q1 having a PNPN four-layer structure as shown in FIG. 2 has been used for controlling large power. This thyristor Q1 can be put into an ignition state by flowing a gate current between the gate terminal G and the cathode terminal K or by irradiating with light, and brings the anode terminal A and the cathode terminal K into a conductive state. Can be held. However, the thyristor Q1 having the PNPN four-layer structure has a drawback that once it is in the ignition state, it cannot be extinguished unless the current flowing from the anode terminal A to the cathode terminal K is sufficiently reduced.

Further, as shown in FIG. 3, the power control element in which the thyristors Q1 and Q2 of the PNPN4 layer structure are connected in antiparallel between the main terminals T1 and T2 can use only the AC power supply as the power supply of the load. If a DC power supply is used as the load power supply, the DC load current cannot be turned off unless the minority carriers are forcibly extracted from the gate terminals G1 and G2 using an external power supply. is there.

[0004]

SUMMARY OF THE INVENTION It is an object of the present invention to solve the above-mentioned drawbacks of the prior art and to provide a semiconductor relay that can be used regardless of whether the power source of the load to be controlled is a DC power source or an AC power source. It is intended.

[0005]

In the semiconductor relay of the present invention, in order to solve the above-mentioned problems, as shown in FIG. Means, the two photodiodes 6 and 7 are optically coupled to the light emitting means, and the anti-series circuit of the two photodiodes 6 and 7 is connected between the collector and base of the transistor 10 in Darlington connection, A resistor R1 is connected between the base and emitter of the transistor 10,
A first circuit in which a diode D1 for blocking a reverse current is connected in series to the emitter of the transistor 10 is connected between the relay output terminals 3 and 4, and two photodiodes 8 and 9 are optically connected to the light emitting means. , And the anti-series circuit of the two photodiodes 8 and 9 is connected between the collector and the base of the transistor 11 connected in Darlington.
A resistor R2 is provided between the base and emitter of the transistor 11.
And a second circuit in which a diode D2 for blocking a reverse current is connected in series to the emitter of the transistor 11 is connected between the relay output terminals 3 and 4 so as to be in antiparallel with the first circuit. It is characterized by that.

[0006]

In the semiconductor relay of the present invention, when an input signal is applied between the relay input terminals 1 and 2, the photodiodes 6, 7, 8 and 9 are brought into conduction by the light irradiation from the light emitting diode 5, and the relay output terminals. Depending on the voltage polarity between 3 and 4,
Either of the two sets of Darlington-connected transistors 10 and 11 is forward-biased to be conductive, and a current flows between the relay output terminals 3 and 4. When the input signal is cut off, the two Darlington-connected transistors 10 and 1 are connected.
When both 1 are in the non-conducting state, the current between the relay output terminals 3 and 4 is cut off.

[0007]

FIG. 1 is a circuit diagram of an embodiment of the present invention. The circuit configuration will be described below. A light emitting diode 5 is connected between the relay input terminals 1 and 2. The light emitted from the light emitting diode 5 is optically coupled to the photodiodes 6, 7, 8 and 9. Between the relay output terminals 3 and 4, the diodes D1 and D are connected to the emitters of the transistors 10 and 11 connected in Darlington, respectively.
A circuit in which two anodes are connected is connected in antiparallel. Photodiodes 6 and 7 connected in anti-series are connected between the base and collector of the first Darlington-connected transistor 10. A resistor R1 is connected between the base and the emitter of the Darlington-connected transistor 10. Photodiodes 8 and 9 connected in anti-series are connected between the base and collector of the second Darlington-connected transistor 11. A resistor R2 is connected between the base and emitter of the Darlington connection transistor 11.

The operation of this embodiment will be described below.
When there is no input signal between the relay input terminals 1 and 2, the light emitting diode 5 does not emit light. At this time, since the anodes / cathodes of the photodiodes 6, 7, 8 and 9 are non-conducting, no current flows through the bases of the transistors 10 and 11 in Darlington connection, and therefore the transistors 10 and 11 in Darlington connection are connected. , And the relay output terminals 3 and 4 are non-conductive regardless of the direction of the applied voltage.

Next, when an input signal is present between the relay input terminals 1 and 2, the light emitting diode 5 emits light.
At this time, a voltage is applied that is sufficient for the light emitted from the light emitting diode 5 to cause a current to flow through the photodiodes 6 and 7, and that the terminal 3 is positive between the relay output terminals 3 and 4. The current flowing through the photodiodes 6 and 7 causes the transistor 1 in Darlington connection
A current flows through the base of 0. Due to this base current, the transistor 10 in Darlington connection becomes conductive, so that the relay output terminals 3 and 4 become conductive and ignite. The diode D1 is for blocking a reverse current.

Here, the terminal 3 is placed between the relay output terminals 3 and 4.
When a voltage that makes the side positive is applied and the semiconductor relay is ignited and the light emission of the light emitting diode 5 stops, the photodiodes 6 and 7 change to the non-conducting state. When no current flows through the base of the transistor 10 and the light emitting diode 5 stops emitting light, the Darlington-connected transistor 10 immediately extinguishes the arc, and the relay output terminals 3 and 4 are also extinguished.

The above description is true even if the direction of the voltage applied between the relay output terminals 3 and 4 of the semiconductor relay has the opposite polarity and the terminal 4 side becomes positive.

In the semiconductor relay of the present invention,
Since the PN junction can be formed between the relay output terminals, a relatively large capacity semiconductor relay can be formed.

[0013]

In the semiconductor relay of the present invention, two Darlington connection transistors are connected in anti-parallel between the relay output terminals, and two reverse terminals optically coupled to the light emitting means connected between the relay input terminals. Since the base current of the Darlington connection transistor flows when the series-connected photodiodes are turned on, it can be used as a semiconductor relay capable of self-extinguishing whether the power supply of the load to be controlled is a DC power supply or an AC power supply. In addition, since this semiconductor relay can be configured only with a PN junction, there is an effect that a large capacity semiconductor relay can be easily configured.

[Brief description of drawings]

FIG. 1 is a circuit diagram of an embodiment of the present invention.

FIG. 2 is a schematic configuration diagram of a conventional example.

FIG. 3 is a schematic configuration diagram of another conventional example.

[Explanation of symbols]

 1,2 Relay input terminal 3,4 Relay output terminal 5 Light emitting diode 6,7 Photo diode 8,9 Photo diode 10 Darlington connection transistor 11 Darlington connection transistor R1 resistance R2 resistance D1 diode D2 diode

Front page continuation (72) Inventor Fumio Kato 1048, Kadoma, Kadoma, Osaka Prefecture Matsushita Electric Works, Ltd. (72) Masato Miyamoto, 1048, Kadoma, Kadoma, Osaka Prefecture Matsushita Electric Works, Ltd.

Claims (1)

[Claims] 1. A collector of a transistor in which a light emitting means is connected between relay input terminals, two light emitting diodes are optically coupled to the light emitting means, and a Darlington connection is made.
A circuit in which an anti-series circuit of the two photodiodes is connected between bases, a resistor is connected between the base and emitter of the transistor, and a diode for reverse current blocking is connected in series to the emitter of the transistor is output as a relay. A semiconductor relay characterized in that two terminals are connected in antiparallel between the terminals.